The techniques conventionally used in the field of the dyeing or bleaching of the hair are targeted at obtaining uniform colours or at obtaining locks having a different colour from the remainder of the head of hair.
Trials have been carried out in order to create areas of non-uniformity in the head of hair by applying, along one and the same lock, one colour and then another, for example, a blonde colouration on the first half of the lock and a brown colouration on the second half. The results obtained on conclusion of these trials can be regarded as unattractive and in general comparable to a colouration obtained after regrowth of the hair.
In some cases, as the hair is sensitized, a dyeing treatment can give non-uniform results which may be regarded as unattractive since they are marked by abrupt transitions from one colour to another.
Furthermore, it is known to treat locks in order to confer, on the head of hair, an appearance similar to that produced by exposure to the sun. The hairdresser then isolates a few locks and applies a bleaching agent to them.
In the case of heads of light hair (blonde or dark blonde hair, for example), the result obtained may be regarded as relatively attractive but is often judged to be rather unnatural.
The attractive nature comes from the fact that each bleached lock opens out towards the tips and thus the light hairs are lost somewhat among the other hairs of the tips. By this opening-out effect, the two colours do not contrast with one another to any great extent.
The rather unnatural character comes from the roots. This is because, on approaching the roots, the hairs of the locks become closer with respect to one another, thus producing an effect of bundles which is rather unnatural as a result of a contrast in colours.
Thus, the locks may give a relatively natural appearance at the tips and at mid-length, while the roots may produce an artificial appearance.
In order to reduce the artificial appearance of the roots, it might be envisaged to decrease the lightening of the hairs of the treated locks. However, such a solution, which reduces the visibility of the lightening, might prove not to be satisfactory. This is because, in order to produce reasonably visible locks, it may be necessary to lighten by approximately 4 tones, such a difference rendering the roots rather unnatural.
Another approach consists in isolating and treating very fine locks. However, this approach is expensive as a result of the time spent by the hairdresser and does not really solve the problem of the visibility of the roots.
Another approach consists in producing the locks starting from the scalp. However, this approach can result in excessive lightening.
There also exists a need to obtain dyed or bleached locks which are thicker and more attractive in order to limit the time spent and to render the service less expensive.
There exists a need to produce locks on heads of dark hair (light chestnut, chestnut, dark chestnut or brown), in particular in order to be able to treat heads of brown hair without having to lighten them beforehand.
The invention is targeted at meeting all or part of the abovementioned needs.